An interview in eight sessions in the summer of 2002 with Hugh P. Taylor, Robert P. Sharp Professor of Geology, emeritus, in the Division of Geological and Planetary Sciences. In this wide-ranging interview, Dr. Taylor recalls his upbringing in Arizona and New Mexico, where his father was an agent for the Santa Fe Railroad; his move to Southern California; and his undergraduate education at Caltech. After receiving his BS at Caltech in geochemistry in 1954 (he was one of the first two geochemistry majors to graduate from the institute), and a master's degree at Harvard, he returned to Caltech for his PhD, working on oxygen-isotope ratios with geochemist Samuel Epstein. He recalls their refinement of the separation technique and his application of Oxygen-18/Oxygen-16 ratios to the study of magmatic intrusions, especially Iceland's Skaergaard intrusion--studies that led to a new understanding of hydrothermal convection and the effects of meteoric groundwater (essentially, rainwater) on basaltic intrusions. He recalls Caltech's move into geochemistry in the early 1950s under the chairmanship of Robert P. Sharp, the advent of plate tectonics in the mid-1960s, the lunar program at Caltech, and his friendship with astronaut/geologist Harrison "Jack" Schmitt. Further recollections include the accomplishments of Gerald J. Wasserburg's laboratory in analyzing the lunar material; Wasserburg's feud with colleague Leon T. Silver; Silver's reluctance to publish; Taylor's collaboration with Silver on isotopic analysis of the Peninsula Ranges Batholith; Taylor's collecting trip to the Skaergaard intrusion; his work with Robert Coleman of the United States Geological Survey on the Red Sea Rift Zone; his work with Bruno Turi on igneous rocks in Italy; and the discoveries made by several of his outstanding graduate students and postdocs. The latter part of the interview amounts to a history of Caltech geology, as he describes the evolution of the division from a classical, field-oriented geology department to a first-rank division incorporating geophysics, geochemistry, and planetary sciences. Along the way, Taylor gives his assessment of the various strengths and weaknesses of the division's chairmen: Robert P. Sharp, Clarence Allen, Eugene Shoemaker, Barclay Kamb, Peter Wyllie, Gerald Wasserburg, Peter M. Goldreich, David J. Stevenson, and Edward M. Stolper.